The cost of transporting and storing fresh milk is significant because of its short shelf life and weight. Because fresh milk is used extensively by America's military and is one of its largest export commodities, there is a long-felt need for a milk concentrate that has a longer shelf life, a product package with a lesser weight for transportation and storage, and that provides the same physical and taste characteristics of fresh milk when reconstituted.
The prior art addresses various aspects of the UHT pasteurization of milk, the production of condensed milk products, and the reconstituting of concentrated liquid beverages. No known prior art, however, discloses an ultra-high temperature pasteurized liquid milk concentrate which may be packaged for dispensing as a reconstituted milk beverage in existing beverage dispensers or for transporting large amounts of UHT pasteurized milk concentrate worldwide to provide a reconstituted milk at the destination that has the same physical characteristics of and tastes like fresh milk.
U.S. Pat. No. 2,860,057 discloses a known preparation of a sterilized evaporated or condensed milk having a final desired concentration of from about 16% to 35% total solids compared to the standard concentration of about 8.0-8.5% total solids. The different processes each involve forewarming and pasteurizing steps including high-temperature-short-term sterilization after the milk is first concentrated by conventional means. The disclosed processing avoids age thickening or gelation of the milk during high-temperature sterilization effected either before or after packaging in a can. If an aseptic canning method is used, the sterilized concentrate is subsequently homogenized under sterile conditions. Reconstitution involves a complicated dilution, mixing, and color comparison procedure with disclosed mixing volume ratio of water to evaporated milk of 1:1.
U.S. Pat. No. 4,921,717 describes a process for producing UHT sterilized concentrated milk including first sterilizing a partially concentrated milk product and then effecting further concentration of the milk product under sterile conditions. U.S. Pat. No. 4,842,884 describes a formulated milk concentrate made with a mixture of nonfat dry milk solids, water, edible oil and sugar. The concentrate can either be frozen for later use or immediately blended with water to produce a beverage. Once reconstituted, it may be stored for up to about 5 days.
U.S. Pat. Nos. 2,570,231; 3,108,875; 4,362,756; and 5,766,666 respectively disclose a sweetened condensed skim milk, condensed cream, condensed milk having at least 8% milk fat, and a reduced fat and/or fat-free condensed milk each processed differently to produce a novel sweetened condensed dairy product in each instance. The condensed cream is used for a source of fat in ice cream. The other three condensed milk products are used in the baking and confectionary industries and by retail consumers to produce baked goods. U.S. Pat. No. 4,091,118 describes a vegetable-based sweetened condensed milk used as a coffee creamer.
U.S. Pat. No. 2,565,085 discloses the customary forewarming of whole milk to destroy bacteria, molds, yeasts, and the like. The forewarming also helps to maintain the texture of the milk product. Such forewarming of the milk is usually effected at a temperature in the range of 145° F. to 175° F. U.S. Pat. No. 5,260,079 describes a method of and equipment for controlling the content of fat in milk using specified process parameters for mixing skim milk with cream. U.S. Pat. Nos. 5,223,299 and 5,229,159 disclose sterilizing milk without stabilizers and a packaged resultant milk concentrate product for use as coffee creamers. U.S. Pat. No. 4,282,262 discloses a milk blend fraction used as an ingredient component for a two-packet frozen dessert. The milk blend includes sodium hexametaphosphate and carrageenan used together as stabilizers.
In brief, in prior practice ultra-high temperature pasteurized (UHT) milk often had a “scorched” or “burnt” milk taste as a result of the extremely high temperature to which the milk is heated in the UHT process. Milk is an extremely heat-sensitive product, in part, because it contains proteins which become denatured at higher temperatures. Such denaturing of the milk results in the scorched milk flavor whereby it loses its fresh milk taste. While improvements have been made in UHT processing for regular strength solids UHT milk products prior to this invention, it was commonly believed in the dairy industry that the problem of scorching would increase as the solids level in milk increases because, in such a concentrated environment, milk proteins would be more susceptible to denaturing at higher temperatures. Known concentrated milk with high milk solids also has a natural tendency to separate or granulate and turn to gel upon aging. Moreover, reconstitution of such a concentrated milk also may lead to granulation and product separation, thus destroying the taste and mouth feel of regular fresh milk.